Vehicular Ad Hoc Network (VANET) supports wireless communication among vehicles using vehicle-to-vehicle (V2V) communication and between vehicles and infrastructure using vehicle-to-infrastructure (V2I) communication. This communication can be utilized to allow the distribution of safety and non-safety messages in the network. VANET supports a wide range of applications which rely on the messages exchanged within the network. Such applications will enhance the drivers' consciousness and improve their driving experience. However, the efficiency of these applications depends on the availability of vehicles real-time location information. A number of methods have been proposed to fulfill this requirement. However, designing a V2V-based localization method is challenged by the high mobility and dynamic topology of VANET and the interference noise due to objects and buildings. Currently, vehicle localization is based on GPS technology, which is not always reliable. Therefore, utilizing V2V communication in VANET can enhance the GPS positioning. With V2V-based localization, vehicles can determine their locations by exchanging mobility data among neighboring vehicles. In this research work, we address the above challenges and design a realistic V2V-based localization method that extends the centroid localization (CL) by assigning a weight value to each neighboring vehicle. This weight value is obtained using a weighting function that utilizes the following factors: 1) link quality distance between the neighboring vehicles 2) heading information and 3) map information. We also use fuzzy logic to model neighboring vehicles' weight values. Due to the sensitivity and importance of the exchanged information, it is very critical to ensure its integrity and reliability. Therefore, in this work, we present the design and the integration of a mobility data verification component into the proposed localization method, so that only verified data from trusted neighboring vehicles are considered. We also use subjective logic to design a trust management system to evaluate the trustworthiness of neighboring vehicles based on the formulated subjective opinions. Extensive experimental work is conducted using simulation programs to evaluate the performance of the proposed methods. The results show improvement on the location accuracy for varying vehicle densities and transmission ranges as well as in the presence of malicious/untrusted neighboring vehicles. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

Neste trabalho, considera-se uma rede sem fio cooperativa em que múltiplas fontes com restrições energéticas cooperam para transmitir informações independentes a um destino comum. Assume-se também que toda a energia disponível nas fontes é captada a partir de transmissões de radiofrequência realizadas pelo destino (o qual é considerado não possuir restrições de energia), sendo dependente das condições instantâneas do canal. Dessa forma, estabelece-se um protocolo de comutação temporal em que em parte do tempo as fontes são carregadas pelo destino, e no restante do tempo transmitem as suas informações. Utilizando-se a probabilidade de outage comométrica de desempenho, analisa-se o desempenho de alguns protocolos cooperativos com transferência sem fio de energia, a saber: decodifica-e-encaminha(EDF), cooperação por codificação de rede (ENC) e cooperação por codificação de rede generalizada (EGNC). Expressões fechadas são desenvolvidas para calcular a probabilidade de outage dos protocolos cooperativos descritos acima, assim como o tempo de carregamento ótimo para minimizar a referida probabilidade e a máxima taxa alcançável para uma probabilidade de outage alvo, mostrando que o protocolo EGNC apresenta o melhor desempenho dentre os protocolos cooperativos considerados e que a transmissão direta (sem cooperação). Simulações numéricas são realizadas para se comprovar a precisão das expressões desenvolvidas e finalmente se enumeram sugestões para a continuação do trabalho. / In this work, we consider a multiuser cooperative wireless network where multiple energy-constrained sources have independent information to transmit to a common destination. The destination, which is assumed to be externally powered, is responsible for transferring energy wirelessly to the sources. The total amount of harvested energy is a function of instantaneous channel conditions. In this scenario, a time-switching protocol is developed where in a fraction of time the sources harvest energy and then use this energy to transmit information. Using the outage probability as a metric, we evaluate the performance of some energy transfer cooperative protocols, namely: energy transfer decode-and-forward (EDF), energy transfer network coding cooperation (ENC) and energy transfer generalized network coding cooperation (EGNC). We obtain a closed-form approximation for the system outage probability, as well as an approximation for the optimal energy transfer period that minimizes such outage probability showing that EGNC protocol presents the best performance among the considered protocols and when compared with the direct transmission. Numerical results are also presented to validate the theoretical results. Finally, suggestions about future works are presented.

Neste trabalho, considera-se uma rede sem fio cooperativa em que múltiplas fontes com restrições energéticas cooperam para transmitir informações independentes a um destino comum. Assume-se também que toda a energia disponível nas fontes é captada a partir de transmissões de radiofrequência realizadas pelo destino (o qual é considerado não possuir restrições de energia), sendo dependente das condições instantâneas do canal. Dessa forma, estabelece-se um protocolo de comutação temporal em que em parte do tempo as fontes são carregadas pelo destino, e no restante do tempo transmitem as suas informações. Utilizando-se a probabilidade de outage comométrica de desempenho, analisa-se o desempenho de alguns protocolos cooperativos com transferência sem fio de energia, a saber: decodifica-e-encaminha(EDF), cooperação por codificação de rede (ENC) e cooperação por codificação de rede generalizada (EGNC). Expressões fechadas são desenvolvidas para calcular a probabilidade de outage dos protocolos cooperativos descritos acima, assim como o tempo de carregamento ótimo para minimizar a referida probabilidade e a máxima taxa alcançável para uma probabilidade de outage alvo, mostrando que o protocolo EGNC apresenta o melhor desempenho dentre os protocolos cooperativos considerados e que a transmissão direta (sem cooperação). Simulações numéricas são realizadas para se comprovar a precisão das expressões desenvolvidas e finalmente se enumeram sugestões para a continuação do trabalho. / In this work, we consider a multiuser cooperative wireless network where multiple energy-constrained sources have independent information to transmit to a common destination. The destination, which is assumed to be externally powered, is responsible for transferring energy wirelessly to the sources. The total amount of harvested energy is a function of instantaneous channel conditions. In this scenario, a time-switching protocol is developed where in a fraction of time the sources harvest energy and then use this energy to transmit information. Using the outage probability as a metric, we evaluate the performance of some energy transfer cooperative protocols, namely: energy transfer decode-and-forward (EDF), energy transfer network coding cooperation (ENC) and energy transfer generalized network coding cooperation (EGNC). We obtain a closed-form approximation for the system outage probability, as well as an approximation for the optimal energy transfer period that minimizes such outage probability showing that EGNC protocol presents the best performance among the considered protocols and when compared with the direct transmission. Numerical results are also presented to validate the theoretical results. Finally, suggestions about future works are presented.

In this thesis we provide a model for a bufferless optical burst switching (OBS) and an optical packet switching (OPS) network. The thesis is divided in three parts. <p><p>In the first part we introduce the basic functionality and structure of OBS and OPS networks. We identify the blocking probability as the main performance parameter of interest. <p><p>In the second part we study the statistical properties of the traffic that will likely run through these networks. We use for this purpose a set of traffic traces obtained from the Universidad Politécnica de Catalunya. Our conclusion is that traffic entering the optical domain in future OBS/OPS networks will be long-range dependent (LRD). <p><p>In the third part we present the model for bufferless OBS/OPS networks. This model takes into account the results from the second part of the thesis concerning the LRD nature of traffic. It also takes into account specific issues concerning the functionality of a typical bufferless packet-switching network. The resulting model presents scalability problems, so we propose an approximative method to compute the blocking probability from it. We empirically evaluate the accuracy of this method, as well as its scalability. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished